1. Field of the Invention
The present invention relates generally to object-oriented computer systems, and in particular, to providing intelligent objects for varying document versions in an object-oriented computer system.
2. Description of the Related Art
In some object-oriented computer systems, an application program or product (e.g., a word processing program or a spreadsheet program) is used to create a file (e.g., a document or spreadsheet). A file from one application can also include one or more objects from another application (e.g., a word processing file may contain a spreadsheet object created using a spreadsheet program). Further, in computer graphics and computer aided design (CAD) programs, drawing elements such as lines, shapes, circles, arcs, etc. may be represented by objects. To associate an object with a specific file, data for the object is streamed out with the file when it is stored.
As application programs are enhanced and updated, newer versions of the application program may be released. Accordingly, the files created by the applications may be tied to or related to a particular application version. Objects and their attributes may evolve over application program versions. Additionally, since the objects are stored with particular versions of a file, the objects are tied to the version of the file. By tying an object to particular version of a file, the evolution of the object is hindered across multiple versions of an application program/product.
For example, if a user wants to save a file in a prior application version (e.g., for use by other users that do not have the most recent version of the application), and the object was created/introduced subsequent to the prior file version, the user has to choose between not evolving the object or not saving the object to the previous file versions.
In another example, an object such as a circle may first be introduced in one version (version A) of an application program and an attribute such as the ability to fill the circle may be introduced in a later version (version B). By tying the object to the file version, the user is forced to choose between not evolving the object (and utilizing the fill attribute) or not saving the object to the previous file version (version A). The fast pace at which products are revised today makes either of these choices unacceptable.
There is a need in the art to enable a user or developer to evolve an object across versions of product releases and still be able to save files to one of the previous product versions.